This invention relates to an image pickup apparatus.
Image pickup apparatus of the retractable barrel type are available wherein a lens barrel in which an image pickup optical system is accommodated is movable between a projecting position in which it projects forwardly of a casing and an accommodated position in which it is accommodated in the casing.
In some of conventional image pickup apparatus of the type described, in order to allow an optical member such as a conversion lens or a filter to be located forwardly of an image pickup optical system, an adapter ring formed in a cylindrical wall shape is removably attached to a threaded portion provided annularly on a front face of the casing such that it surrounds the lens barrel. The optical member is removably attached to a front end of the adapter ring. One of the image pickup apparatus of the type just described is disclosed, for example, in Japanese Patent No. 3174205 (hereinafter referred to as Patent Document 1).
Another one of the image pickup apparatus of the type described above is disclosed, for example, in Japanese Patent Laid-open No. Hei 10-48737 (hereinafter referred to as Patent Document 2). In the image pickup apparatus, an optical member including an adapter for three-dimensional image pickup is removably attached to a front end of a lens barrel, and a detection switch which exhibits an on state when the optical member is attached to the lens barrel is provided at a front end of the lens barrel. The image pickup apparatus records identification data on a film based on the operation of the detection switch.
In the image pickup apparatus of the Patent Document 1, the image pickup optical system is formed from a zoom lens, and the projection amount of the lens barrel varies in response to the zooming operation. Where it is taken into consideration to attach an optical member to the adapter ring, when the lens barrel is positioned at the most projecting position, the front end of the lens barrel must not interfere with the optical member attached to the adapter ring.
Therefore, in order to assure the distance between the optical member and the front end of the lens barrel, it is necessary to form the adapter ring and the optical member with great dimensions in the direction of the optical axis of them. Further, in order to prevent appearance of an eclipse with the image pickup optical system, also the dimension in a diametrical direction of the adapter ring and the optical member must be set great. Accordingly, the image pickup apparatus of the Patent Document 1 is disadvantageous in that increase in scale, weight and cost of the adapter ring and the optical member cannot be avoided.
Meanwhile, although the image pickup apparatus of the Patent Document 2 detects attachment of an optical member to the lens barrel and performs predetermined control, the Patent Document 2 is silent of interference of the front end of the retractable lens barrel with the optical member attached to the adapter ring.